It is proposed that a central depository of pedigreed transplantable hepatoma tumor lines be maintained and disseminated from Howard University Medical School where complete records are available for any information needed by basic cancer research investigators. The spectrum of transplantable tumors are made up of more than 30 different tumor lines. The hepatomas differ in growth rate by more than 20-fold. They are divided among slow growing highly differentiated; intermediate growth rate well differentiated; and fast growing poorly differentiated tumor lines. Investigators from all parts of the United States and abroad make requests for suitable basic cancer research materials and are advised as to which hepatoma lines are most suitable for the type of research they propose. In addition, investigators at Howard University Medical School make use of this spectrum of tumors. We propose to induce adenocarcinomas in the regenerating liver of the rat after a single dose of strongly acting chemical carcinogens; chromosome banding analyses will be made of a selected spectrum of tumors; the hybridization of rat hepatoma cells and mouse cells will be performed in attempts to relate specific chromosomes or a specific complement of chromosomes to malignancy; an evaluation of hepatoma microtubule structure and mitotic spindle formation will be accomplished; development of frozen storage-retrieval techniques will be carried out on this spectrum of transplantable tumors; studies on the mechanism of metastases formation will be performed.